Demand Response and Reliability

Renewable Resources, Especially Variable Generation, Require a “Dancing Partner,” a resource that can complement increasing penetration of wind and solar, and provide operational flexibility to maintain reliability during the sharp down-ramps that can be experienced with these resources. With all the interest around renewables, it's sometimes easy to overlook some of the greatest potential for driving long-term sustainability: better electricity management through energy efficiency and peak load management.

Demand response (DR) has many qualities that make it particularly well-suited to play this role, and, indeed, we are already seeing it step on to the dance floor, so to speak. In addition to its ability to target peak demand growth, communications technologies have made the resource more dispatchable than ever before, in many cases available to operators in a matter of minutes. In fact, DR is increasingly being classified as non-spinning reserves and used as “ancillary services” by many utilities, as shown in data collected for NERC's 2007 Summer Reliability Assessment.

GROWTH IN DEMAND RESPONSE

DR has long been a vital contributor to reliability, but it is now on the brink of becoming much more. Significant increases in DR were evident in the Midwest and Northeast when looking at year-to-year comparisons between 2007 and 2008. Key enabling technologies — such as new smart meters and home automation systems — are opening up even wider opportunities for the resource.

The existing design of the bulk power system is based on the development of large central stations and subsequent delivery to demand centers through T&D. Up until recently, DR and advanced metering have been viewed as an add-on toward supporting this fundamental design. However, new technologies are beginning to push the grid from this essentially static analog design into a more flexible, robust digital system that is better suited to the operation of variable resources such as wind, solar and wave energy.

As the Smart Grid begins to develop further, more work will be needed to incorporate new resources — like distributed generation, demand response and plug-in electric hybrid vehicles — into reliability planning and operations.

IMPROVING RELIABILITY

DR has the potential to “dance” with several of these new resources, supporting reliability and helping operators manage growing peak demand by helping to reduce congestion on critical transmission lines, enabling more efficient use of variable generation and energy-only resources, and, ultimately, improving reliability. Advanced communications and control will only add to the resource's flexibility, effectively enabling the transformation of commercial applications to emergency applications and vice versa.

As we look into the Smart Grid of the future, it's clear that DR will continue to be a key contributor to reliability. The only thing left to determine is whether this dancer will specialize in tango, ballet, tap or jazz.

Mark G. Lauby is manager of reliability assessments for the North American Electric Reliability Corporation.mark.lauby@nerc.net